Dental-chair jack



D. C. HAYDEN.

DENTAL CHAIR JACK.

APPLICATION FILED AUG-f9, 1920.

1,387,541. PatentedAug. 16,1921.

i z.5 W 3 i UNITED STATES I DONALD C. HAYDEN, 0F BRIDGEPORT, CONNECTICUT.

DENTAL-CHAIR JACK.

Specification of Letters Patent. Patented Aug. 16', 1921.

Application filed August 19, 1920. Serial No. 404,702.

T 0 (NZ IlilO-HZ- it may concern:

e it known that I, DONALD C. HAYDEN, a citizen of the United States, residing at the city of Bridgeport,- in the county of Fairfield and State of Connecticut, have invented certain new and useful Improvements in Dental-Chair Jacks; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which 1t appertains to make and use the same.

This invention relates to certain new and useful improvements in an electrically operated jack for dental chairs and it has for the primary objects to provide a jack or chair pedestal of sim ple construction suit able for dentists, barbers, and for usages to which fluid operated jacks have heretofore been employed.

The invention further resides in the features of construction and the arrangements and combinations of parts resulting in an improved construction which will be efiicient and practical in operation, reference being made to the accompanying drawings wherein the view is a vertical section through the chair pedestal and its electric extending and telescoping jack.

The drawing shows a vertical sectional view of the invention in wh1ch the chair pedestal is mounted on a base 1, and comprises a plurality of telescopic sections 2, 3 and 4, the lower section 2 having a bottom 5 closing its lower end and provlding a rest or support for the pedestal-extending jack which is inclosed within the pedestal.

The jack comprises a hollow base 6 constituting a gear case and having a cover plate 7 which is removably secured thereto by screws 8, supports the motor housing 9 that incloses a reversible electric motor. The housing is equipped with depending legs 10 having inturned feet 11 which are connected to the cover 7 by detachable fastening 12.

The motor shaft 13 is detachably coupled to a gear shaft 14 by a sleeve 15 keyed thereto so as to be removed for repair, said gear shaft passing through a bushing 16 threaded through the cover plate and capable of exerting a confining pressure on the upper and lower ball bearings 17 between wh1ch is interposed the gear 18. This gear, in turn, meshes with a similar gear 19 which is mounted on a right angularly disposed shaft 20 and may be equip ed with thrust ball bearings (not shown The intermediate idler gear 19 meshes with a larger gear 21 which is disposed in the plane of gear 18 and 1s fixed on the lower end of the vertical jack screw shaft 22, the latter "being journaled in the gear case and supported with the gear by thrust ball bearing 23. A bushing 24 surrounds the shaft and bears at its lower end on the gear, preferably in an anti-frictional manner.

The jack shaft is screw threaded throughout its length above the gear case and has a sleeve-like nut 25 engaged with its threads whereby upon rotation of the shaft the out will be correspondingly raised or lowered. The elevating and lowering member 26 is in the form of a tube secured at its lower end to the nut, so as to telescope the jack shaft, and has fixed in its upper end a plug 27 which projects above the tube in theform of a square shank 28 that passes through a similar opening in a bracket 29 and is secured thereto by the nut.30 threaded on the upper end of the plug. The bracket is secured to the uppermost pedestal section 4 whereby as the tube is extended relative to the shaft the pedestal sections will also be extended upwardly and when the motor is reversed the operation will be the opposite, namely, a telescoping of the pedestal sections and the jack shaft and tube.

The motor is preferably connected to a foot-operated switch disposed so as to be easily accessible by the dentist or barber, or a suitable manual control can be provided. The operating mechanism is all arranged at the base of the pedestal and concealed within the latter. No physical exertion, such as pumping for a hydraulic jack, is required. The control and operation 15 reliable, steady and quickly responsive to the command of the operator. The reversible motor, which revolves in one direction for elevating the chair and in the opposite direction for lowering the same, obviates the necessity of clutch mechanisms, thereby sim lifying the construction and operation. bviously the jack can be employed for other structures than those specifically referred to and it is therefore not the intention to limit the invention by any recitation as to a particular embodiment.

What is claimed is:

1. In an electrically operated jack for dental chairs, embodying a telescopic pedestal, a screw threaded jack shaft within the lower pedestal section, a telescopically related elevating member engaged with the threads thereof and carried by the upper pedestal section, a gear fixed on the lower end of the shaft within a gear case, an electric motor supported over the latter, a shaft journaled in the case in alinement with the motor shaft, means detachably coupling the motor shaft and its alined shaft whereby the motor may readily be lifted off the gear case, and a gear on the latter shaft operatively connected to the first gear.

2. An electrically operated jack for dental chairs embodying a telescopic pedestal, comprising a gear ease disposed in the base of the latter, gearing within the gear case, a removable cover plate for the latter, a motor housing having supporting legs attached to the cover plate for supportin a motor spaced thereabove, a shaft journa led in the cover plate and extending upwardly into the space between the supporting legs for connection with themotor shaft, and an extensible jack shaft journaled in the cover plate and extending upwardly alongside the motor housing with its upper end connected to the upper edestal section.

3. In an e ectrically operated jack for nection in the gear chairs, a telescopic pedestal, a gear case in the lower pedestal section, a threaded shaft journaled at its lower end in the gear case, a tubular member carried by the upper pedestal ection and threadedly engaged over the shaft, :1 gear on the lower end of the shaft, a motor, means to removably support the motor from the gear case, a driving concase engaged with the shaft gear and including a part extending out from the gear case, and a detachable coupling between the motor and said lastnamed part.

4.111 an electrically operated jack for chairs, a telescopic pedestal, a gear case in the lower pedestal section, a cover for the gear case, a threaded shaft journaled in the gear case, means borne by the upper pedestal section engaging the shaft threads to be operated by the shaft, a shaft journaled in the gear case and cover and extending above the latter, a driving connection between said shafts, a motor on the cover, and a detachable connection between the motor and the extension of the second named shaft.

In testimony whereof I affix my signature.

DONALD C. HAYDEN. 

